The present invention relates to a non-contact charging method and a non-contact charging system for carrying out electric power transmission to a vehicle in a contactless manner.
For electric vehicles such as electric-powered cars and hybrid cars, it is necessary to charge an in-vehicle electricity storage device from a power supply outside the vehicle. In this regard, a non-contact power supply method without using a cable draws attention as a method of supplying electric power to a vehicle from outside of the vehicle. As a non-contact power supply method, there is, e.g., a method by means of electromagnetic coupling (a method by means of electromagnetic induction, a method by means of electromagnetic waves, a resonance method, etc.). Patent Document 1 discloses a non-contact power supply system utilizing a resonance method.
Non-contact power supply to a vehicle is non-contact power supply of heavy current, unlike non-contact power supply of weak current which is performed for mobile terminals or the like. In the case of non-contact power supply of heavy current, electromagnetic waves that are generated during power supply operation have an influence on not only human body, but also various electric products. Investigating use cases in which non-contact power supply is practically applied reveals that there appears to be a possibility that the user of an electric vehicle starts charging, while leaving an electronic appliance such as a product of consumer electronics in the electric vehicle. If doing so, the electronic appliance left in the electric vehicle may be heated to high temperature by electromagnetic waves which are generated when electricity is charged to the electric vehicle and, eventually, there is a possibility that the electronic appliance fails.
In Patent Document 2, described is a technique that prevents efficiency of power supply from decreasing by an intervening foreign matter. According to this technique, before starting non-contact power supply, precharging is performed to detect whether or not a foreign matter is present between a power supply coil of a power supply device and a power receiving coil in the vehicle.